Transplantation Immunology.pdf - E-Lib FK UWKS

Status of Liver Transplantation 31
outcome and value to society were a greater priority. Patients who displayed
traits consistent with antisocial behavior (e.g., alcoholism) were given a low
level of importance by all. In general, the indications for liver transplantation
can be defined as either an intolerable quality of life (because of the liver disease)
or an anticipated length of life of less than 1 yr because of liver failure.
3. Organ-Allocation Policies
Various schemes have evolved to allocate organs with some reference to
urgency. In the United States, the Model for End-Stage Liver Disease (MELD)
score, based on serum creatinine, bilirubin, and international normalized ratio
(INR), was developed initially during a retrospective study at the Mayo Clinic
of patients undergoing transhepatic portosystemic shunts (TIPS). It was subsequently
validated as a determinant of short-term prognosis in patients with
chronic liver disease (9) and utilized as a disease severity index. In February
2002, the MELD score was implemented by the United Network for Organ
Sharing (UNOS) as a criterion for organ allocation to adult patients with
chronic liver disease followed the ruling of the Department of Health that allocation
be conducted according to medical urgency. Priority is still given to
status 1 patients (fulminant hepatic failure or early graft failure following transplantation
requiring emergency re-transplantation); these remain a local and
regional priority. After these patients, livers are offered to patients based upon
their probability of candidate death derived from MELD scores. With a MELD
score of 6 or less, the time on the waiting list is also used as a prioritization
factor (10). Early reports indicate that this allocation system based on medical
severity may reduce the number of deaths on the waiting list (11).
In the United Kingdom, four fundamental concepts underpin the allocation
policy, as agreed at the Edinburgh colloquium in 1996 (12). First, guidelines
need to be drawn up and agreed on by all those involved. Second, the main
criteria for selection must be based on quality of life and anticipated life
expectancy. Third, patients selected for transplantation should have a more
than a 50% probability of being alive 5 yr after the transplant. Finally, livers
are allocated to give the maximum outcome (in preference to every potential
recipient having equal share of the donor pool by right). Thus, it is generally
agreed that organ allocation should be based on utilitarian rather than
deontological principles.
In UK practice, certain patients (those with either fulminant liver failure or
primary nonfunction of a transplant—the equivalent of UNOS status 1) have
national priority (these patients are deemed “super-urgent”). Thereafter, livers
are offered first to the retrieving unit and then, if there is no suitable recipient
locally, around the rest of the country on a continually rolling priority based on
the balance of net export at each individual center. Thus, livers are allocated to